The present invention relates, in general, to an electric machine, and more particularly to an electric machine having a stator with slots for positioning tooth coils.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Coils of electric machines are positioned in slots, i.e. the coils are prefabricated and then positioned in the slots of the electric machine. Machines are also known having pronounced windings to form tooth coils, whereby each winding surrounds a single tooth. These prefabricated tooth coils are positioned from outside into a star-shaped coil bobbin constructed in the form of a stacked metal sheets and pushed into a stator yoke. It is also possible to fabricate the windings of electric machines in the form of prefabricated coils which are then fed-in wire by wire into the slots of the stator. This is time-consuming and labor intensive.
Common to all these approaches is also the very complicated manufacture. In addition, these approaches lead to large end windings, and the slot filling factor is relatively low. Especially when a two-part lamination piece is involved, the provision of webs between the stator teeth is required to ensure a mechanical stability of the star-shaped packet. As a consequence, part of the flux which could assist the torque formation is shorted and thus becomes ineffective.
It would therefore be desirable and advantageous to provide an improved electric machine to obviate prior art shortcomings and to allow easy placement of a winding in the slots.